A method has been conventionally available in which paste solder is applied onto a printed circuit board (hereinafter, referred to as a “board”) by using a printing technique, electronic components are mounted on the applied solder, and then, reflowing (heating and cooling) is performed to fix the electronic components on the board.
Since a number of electronic components are usually mounted on a board, on a line for mounting electronic components by using solder, after the electronic components are mounted, the state of mounting the electronic components (that is, whether or not the electronic components are mounted on predetermined positions) is inspected before reflowing.
Incidentally, since confirmation is made only for the position of a mounted electronic component and the presence or absence of the electronic component, when the absence of electronic component is confirmed, it is not possible to recognize whether or not the electronic component is actually conveyed onto solder. Therefore, regarding an error indicative of the absence of an electronic component, an operator has to take time to adjust apparatuses while assuming various causes. This operation is one of the causes of lower productivity.